PURPOSE: Craniofacial venous malformations (VMs) are challenging lesions. Treatment is not routinely indicated unless the benefit and loss have been weighed properly. Therefore it is crucial to predict clinical outcome before treatment. This study was performed to retrospectively determine whether pretreatment magnetic resonance imaging (MRI) findings are predictive of outcome in patients who undergo sclerotherapy for craniofacial VMs. PATIENTS AND METHODS: MRI findings and clinical results of percutaneous sclerotherapy with ethanol and bleomycin A(5) in 69 patients with craniofacial VMs were retrospectively reviewed. Lesions were categorized with MRI based on margins; 51 were limited VMs, and 18 were infiltrating VMs. We performed t test analysis to assess the difference in the number of sclerotherapy sessions between the 2 groups. The Kruskal-Wallis test was used to evaluate differences in symptom improvement and satisfaction level between the groups. The difference in complication rates was assessed by chi(2) analysis. RESULTS: The better response to treatment was among the patients with limited VMs. The number of sclerotherapy sessions was 1.9 +/- 1.2 for limited VMs and 3.6 +/- 1.5 for infiltrating VMs, with a significant difference between the groups (P = .0001). The patients with limited VMs were significantly more likely to have better symptom improvement (P = .0001) and a higher satisfaction level (P = .0001). The complication rates of the limited and infiltrating VMs were 18.2% (18/99) and 32.8% (21/64), respectively. A significant difference was found between the groups (P = .033). CONCLUSIONS: The feature of lesion margin on MRI before sclerotherapy is an important predictor of treatment outcome for craniofacial VMs.